Curable composition

ABSTRACT

The present application relates to a curable composition. A curable composition may be provided; which shows excellent processability and workability; which shows excellent light extraction efficiency, crack resistance, hardness, thermal shock resistance and adhesive strength after curing; and which has excellent reliability and long-term reliability under high-temperature and/or high-moisture conditions. Also, turbidity and surface stickiness may be prevented in the cured product.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/554,489, filed on Jul. 20, 2012, which is a continuationapplication of International Application PCT/KR2011/000520, with aninternational filing date of Jan. 25, 2011, which claims priority to andthe benefit of Korean Patent Application No. 10-2010-0006699, filed Jan.25, 2010, and of Korean Patent Application No. 10-2011-0007454, filedJan. 25, 2011, the disclosure of which are incorporated herein byreference in their entireties.

TECHNICAL FIELD

The present application relates to a curable composition.

BACKGROUND ART

As a light emitting diode (LED), particularly as a blue or UV LED havingan emission wavelength of approximately 250 nm to 550 nm, ahigh-brightness LED product using a compound semiconductor made of a GaNcompound such as GaN, GaAlN, InGaN or InAlGaN has been obtained. Also, ahigh-definition full color image may be formed using a technique ofcombining red and green LED's with a blue LED. For example, a techniqueof preparing a white LED by combining a blue LED or UV LED with aphosphor has been known. Such LED's have been increasingly required forbacklighting or general lighting in liquid crystal displays (LCD's).

As an LED encapsulant, an epoxy resin having high adhesive strength andexcellent dynamic durability has been widely used. However, the epoxyresin has problems in that it has low transmittance with respect tolight having blue to UV wavelength regions, and also shows poorlightfastness. Therefore, techniques in order to solve the problems asdescribed above have been proposed, for example, in Japanese PatentLaid-Open Publication Nos. Hei11-274571, 2001-196151 and 2002-226551.However, the encapsulants described in these literatures showinsufficient lightfastness.

As a material that has excellent lightfastness with respect to the lowwavelength range, a silicone resin has been known. However, the siliconeresin has disadvantages in that its heat resistance is poor, and itssurface becomes sticky after curing. Also, in order to effectively applythe silicone resin as an LED encapsulant, characteristics such as a highrefractive property, crack resistance, surface hardness, adhesivestrength and thermal shock resistance must be secured.

DISCLOSURE Technical Problem

The present application provides a curable composition.

Technical Solution

The present application relates to a curable composition. The curablecomposition may include (A) a polymerized product; (B) a crosslinkedorganosiloxane compound, which is represented by an average compositionformula of Formula 2 and of which a molar ratio of an alkenyl groupbound to a silicon atom with respect to the total silicon atoms rangesfrom 0.15 to 0.35; and (C) a hydrogen siloxane compound, which isrepresented by Formula 3 and of which a molar ratio of a hydrogen atombound to a silicon atom with respect to the total silicon atoms rangesfrom 0.2 to 0.8. The polymerized product may include a linearorganosiloxane compound, which is represented by an average compositionformula of Formula 1 and of which a molar ratio of an alkenyl groupbound to a silicon atom with respect to the total silicon atoms rangesfrom 0.02 to 0.2.

In the curable composition, the organosiloxane compound (B) is includedin a weight ratio of 50 parts by weight to 700 parts by weight relativeto 100 parts by weight of the linear organosiloxane compound included inthe polymerized product (A).

In the curable composition, a molar ratio of the hydrogen atom bound toa silicon atom in compound (C) with respect to the alkenyl group boundto a silicon atom in the linear organosiloxane compound of thepolymerized product (A) and the crosslinked organosiloxane compound (B)is in a range of 0.8 to 1.2.

(R¹R²R³SiO_(1/2))_(a)(R⁴R⁵SiO_(2/2))_(b)(R⁶SiO_(3/2))_(c)(SiO_(4/2))_(d)  [Formula1]

(R⁷R⁸R⁹SiO_(1/2))_(e)(R¹⁰R¹¹SiO)_(f)(R¹²SiO_(3/2))_(g)(SiO_(4/2))_(h)  [Formula2]

wherein R¹ to R¹² each independently represent an alkoxy group, ahydroxy group, an epoxy group or a monovalent hydrocarbon group, withthe provision that at least one of R¹ to R⁶ is an alkenyl group and atleast one of R⁷ to R¹² is an alkenyl group; R's independently representhydrogen, an epoxy group or a monovalent hydrocarbon group; a is in arange of 0 to 0.5, b is in a range of 0.5 to 0.98, c is in a range of 0to 0.2, d is in a range of 0 to 0.1, e is in a range of 0 to 0.5, f isin a range of 0 to 0.3, g is in a range of 0.3 to 0.85, h is in a rangeof 0 to 0.2, n is in a range of 1 to 10, with the provision that a+b+c+dis 1 and e+f+g+h is 1.

The curable composition may be cured through the reaction of the alkenylgroup bound to a silicon atom of the linear organosiloxane compound ofthe polymerized product (A) and the crosslinked organosiloxane compound(B) with the hydrogen atom bound to a silicon atom of compound (C). Thecurable composition shows excellent processability and workability, andmay provide a cured product thereof that has excellent crack resistance,hardness, thermal shock resistance and adhesive strength. The curablecomposition shows excellent long-term reliability even under severeconditions such as high-temperature and/or high-moisture conditions. Thecurable composition does not cause turbidity or surface stickiness underthese severe conditions.

The curable composition includes the polymerized product (A) includingthe linear organosiloxane compound represented by the averagecomposition formula of Formula 1. In this specification, anorganosiloxane compound represented by a certain average compositionformula may mean cases where the compound comprises a single componentthat is represented by the certain average composition formula, as wellas cases where the compound includes a mixture of at least twocomponents and an average composition of the two components isrepresented by the certain average composition formula.

In the average composition formula of Formula 1, R¹ to R⁶ aresubstituents directly bound to a silicon atom, and independentlyrepresent an alkoxy group, a hydroxy group, an epoxy group or amonovalent hydrocarbon group. In the above, examples of the monovalenthydrocarbon group may include an alkyl group, a halogenated alkyl group,an alkenyl group, an aryl group and an arylalkyl group. In the above,the alkoxy group or the monovalent hydrocarbon group may be substitutedwith a suitable substituent, if necessary.

In the average composition formula, the alkoxy group may be a linear,branched or cyclic alkoxy group having 1 to 12 carbon atoms, preferably1 to 8 carbon atoms, and more preferably 1 to 4 carbon atoms, and maypreferably include a methoxy group, an ethoxy group or a propoxy group.

In the average composition formula, the alkyl group or the halogenatedalkyl group may be a linear, branched or cyclic alkyl group orhalogenated alkyl group having 1 to 12 carbon atoms, preferably 1 to 8carbon atoms, and more preferably 1 to 4 carbon atoms, and maypreferably include a methyl group, an ethyl group, a propyl group, achloromethyl group, a 3-chloropropyl group or a 3,3,3-trifluoropropylgroup, while a methyl group is more preferred.

Also in the average composition formula, the alkenyl group may be analkenyl group having 2 to 12 carbon atoms, preferably 2 to 8 carbonatoms, and more preferably 2 to 4 carbon atoms, and may preferablyinclude a vinyl group, an allyl group, a butenyl group, a pentenyl groupor a hexenyl group, while a vinyl group is more preferred.

Also in the average composition formula, the aryl group may be an arylgroup having 6 to 18 carbon atoms, and preferably 6 to 12 carbon atoms,and may preferably include a phenyl group, a tolyl group, a xylyl groupand a naphthyl group, while a phenyl group is more preferred.

Also in the average composition formula, the arylalkyl group may be anarylalkyl group having 6 to 19 carbon atoms, and preferably 6 to 13carbon atoms, and may preferably include a benzyl group or a phenethylgroup.

In Formula 1, at least one of R¹ to R⁶ is an alkenyl group.Specifically, the alkenyl group may be included in such an amount thatthe molar ratio (Ak/Si) of the alkenyl group (Ak) bound to a siliconatom with respect to the total silicon atoms (Si) in the linearorganosiloxane compound in the polymerized product (A) is in a range of0.02 to 0.2, preferably 0.02 to 0.15. If the molar ratio (Ak/Si) is notless than 0.02, it is possible to suitably maintain reactivity with thecomponent (C), and prevent components that have not reacted frombleeding on the surface of the cured product. Also, if the molar ratio(Ak/Si) is not more than 0.2, it is possible to maintain excellent crackresistance of the cured product.

Also, in Formula 1, at least one of R¹ to R⁶ may be an aryl group,preferably a phenyl group. Therefore, the refractive index and hardnesscharacteristics of the cured product may be effectively controlled.Specifically, the aryl group, preferably the phenyl group, may beincluded in such an amount that the molar ratio (Ar/Si) of the arylgroup (Ar) with respect to the total silicon atoms (Si) in the linearorganosiloxane compound in the polymerized product (A) is in a range of0.3 to 1.3, preferably 0.4 to 1.3, and more preferably 0.6 to 1.3. Ifthe molar ratio (Ar/Si) is not less than 0.3, it is possible to optimizethe refractive index and hardness of the cured product, and if the molarratio (Ar/Si) is not more than 1.3, it is possible to optimize viscosityof the composition.

In the above, a, b, c and d in the average composition formula ofFormula 1 may represent molar ratios of the siloxane units,respectively, and the total sum of a, b, c and d is 1; a is in a rangeof 0 to 0.5, b is in a range of 0.5 to 0.98, c is in a range of 0 to0.2, and d is in a range of 0 to 0.1. In order to optimize the crackresistance of the cured product, (a+b)/(a+b+c+d) may be controlled to begreater than 0.9, preferably greater than 0.95. For example, the upperlimit of (a+b)/(a+b+c+d) may be 1.

In the above, the polymerized product (A) may have a viscosity at 25° C.of 1,000 mPa·s to 100,000 mPa·s, preferably 1,000 mPa·s to 50,000 mPa·s.If the viscosity falls within the range, it is possible to maintainexcellent processability and workability of the composition beforecuring and to optimize hardness of the composition after curing.

The linear siloxane compound included in the polymerized product (A) orthe product (A) may have a weight average molecular weight (M_(w)) of,for example, 1,000 to 50,000, preferably 1,000 to 30,000. If the M, ofthe organosiloxane compound (A) is not less than 1,000, it is possibleto provide a composition that shows an appropriate viscosity and hasexcellent intensity and crack resistance after curing. Also, if themolecular weight (M_(w)) is not more than 50,000, it is possible tooptimize viscosity of the composition, thereby maintaining excellentworkability and processability. In this specification, the term “weightaverage molecular weight” or “M_(w)” may refer to a value converted withrespect to standard polystyrene and measured by gel permeationchromatography (GPC). Also, unless stated otherwise, the term “molecularweight” means a weight average molecular weight hereinafter.

In one embodiment, an organosiloxane compound represented by theformulas below may be used as the linear organosiloxane compound, butnot limited thereto.

(ViMe₂SiO_(1/2))₂(MePhSiO_(2/2))₃₀;

(ViMe₂SiO_(1/2))₂(Ph₂SiO_(2/2))₁₀(Me₂SiO_(2/2))₁₀;

(ViMe₂SiO_(1/2))₂(MePhSiO_(2/2))₂₀(Ph₂SiO_(2/2))₁₀(Me₂SiO_(2/2))₂₀;

(ViMe₂SiO_(1/2))₂(MePhSiO_(2/2))₅₀(Me₂SiO_(2/2))₁₀;

(ViMe₂SiO_(1/2))₂(Me₂SiO_(2/2))₅₀(Ph₂SiO_(2/2))₃₀(PhSiO_(3/2))₅;

(ViMe₂SiO_(1/2))₂(ViMeSiO_(2/2))₂(Me₂SiO_(2/2))₃₀(Ph₂SiO_(2/2))₃₀.

In the formulas, “Vi” represents a vinyl group, “Me” represents a methylgroup, and “Ph” represents a phenyl group.

The linear organosiloxane in the product (A) or the product (A) mayinclude at least one difunctional siloxane unit represented by Formula 5and at least one difunctional siloxane unit represented by Formula 6.

(R¹³R¹⁴SiO)  [Formula 5]

(R¹⁵R¹⁶SiO)  [Formula 6]

wherein R¹³ and R¹⁴ independently represent an alkyl group, and R¹⁵ andR¹⁶ independently represent an aryl group. In Formulas 5 and 6, specificexamples of the alkyl and aryl groups may be the same as in Formula 1

In one embodiment, the molar ratio (100×D₆/D) of the difunctionalsiloxane unit (D₆) of Formula 6 with respect to the total difunctionalsiloxane units (D) in the organosiloxane compound (A) may be 30% ormore. The molar ratio (100×D₆/D) may also be in the range from 30% to65% or from 30% to 60%. If the molar ratio (100×D₆/D) is 30% or more, itmay be possible to provide the cured product capable of preventingtackiness on the surface from being generated and having excellentmechanical strength, water and gas transmission properties, andlong-term reliability even under high-temperature and/or high-moistureconditions.

The polymerized product (A) may include low-molecular weight cycliccompounds. The term “low-molecular weight cyclic compound” used hereinmay refer to a cyclic compound, of which the molecular weight is notmore than 800, not more than 750 or not more than 700. The cycliccompound may be represented by Formula 7 below.

wherein R^(e) and R^(f) independently represent an alkyl group, R^(g)and R^(h) independently represent an aryl group, q is 0 or a positivenumber, r is 0 or a positive number, and g+r is in a range from 3 to 10,from 3 to 9, from 3 to 8, from 3 to 7 or from 3 to 6. In Formula 7,specific examples of the alkyl and aryl groups may be the same as inFormula 1.

The product (A) may include the cyclic compounds in an amount of 10weight % or less, 7 weight % or less, 5 weight % or less or 3 weight %or less. The cyclic compound may be included in the product (A) in anamount of 0 weight % or more, or 1 weight % or more. If thelow-molecular weight cyclic compounds are included in an amount of 10weight % or less, it may be possible to provide the cured product havingexcellent crack resistance, and long-term reliability even underhigh-temperature and/or high-moisture conditions. The weight ratio ofthe cyclic compounds may be controlled by eliminating the cycliccompounds remained in the product (A) after the polymerization processthrough conventional purification processes.

In one embodiment, the polymerized product (A) may be a ring-openingpolymerization reaction product of a mixture comprising a cyclicorganosiloxane compound. The cyclic organosiloxane compound may berepresented by Formula 8 below.

wherein R^(a) and R^(b) independently represent an alkoxy group, ahydroxy group, an epoxy group or a monovalent hydrocarbon group, and pis in a range from 3 to 9, from 3 to 8, from 3 to 7 or from 3 to 6. InFormula 8, specific examples of the alkoxy and monovalent hydrocarbongroups may be the same as in Formula 1. Also, R^(a) and R^(b) may beselected in such a way that the linear organosiloxane compound may beproduced.

In one embodiment, the mixture may include at least one compound ofFormula 8, in which both of R^(a) and R^(b) are alkyl groups, and atleast one compound of Formula 8, in which both of R^(a) and R^(b) arearyl groups.

The mixture may further include at least one compound represented byFormula 9 below.

(R^(c)R^(d) ₂Si)₂O  [Formula 9]

wherein R^(a) to R^(d) independently represent an alkoxy group, ahydroxy group, an epoxy group or a monovalent hydrocarbon group, and pis in a range of 2 to 10. In Formula 9, specific examples of the alkoxyand monovalent hydrocarbon groups may be the same as in Formula 1. Also,R^(c) and R^(d) may be selected in such a way that the linearorganosiloxane compound may be produced.

In the above mixture, the specific kinds of substituents, the weightratio of components, and the like may be selected in such a way that thelinear organosiloxane compound may be produced.

The ring-opening polymerization may be performed in the presence of asuitable catalyst. Therefore, the mixture may further include at leastone catalyst.

As the catalyst, a base catalyst may be used. Suitable catalysts may bemetal hydroxides such as KOH, NaOH or CsOH; metal silanolates includingan alkali metal compound and a siloxane compound; or quaternary ammoniumcompounds such as tetramethylammonium hydroxide, tetraethylammoniumhydroxide or tetrapropylammonium hydroxide, but not limited thereto.

The weight ratio of the catalyst in the mixture may be suitablycontrolled considering reactivity, and the like. For example, thecatalyst may be included in the mixture in an amount of 0.01 to 30 partsby weight or 0.03 to 5 parts by weight, relative to 100 parts by weightof the total reactants.

In one embodiment, the ring-opening polymerization may be performed insuitable solvents. The specific kinds of the solvents are notparticularly limited, but may be selected so as for the reactants suchas the cyclic organosiloxane compound and the catalyst to be uniformlymixed and so as not to adversely affect the reactivity.

The polymerization may be performed in the temperature from 0° C. to150° C. or from 30° C. to 130° C. The polymerization may be performedfor 1 hour to 3 days.

The curable composition includes the crosslinked organosiloxane compound(B) that is represented by an average composition formula of Formula 2.The term “crosslinked organosiloxane compound” used herein refers to asiloxane compound that essentially includes a siloxane unit representedby (RSiO_(1.5)) or (SiO₂). In the above, R may be an alkoxy group, ahydroxy group, an epoxy group or a monovalent hydrocarbon group asdescribed in Formula 1.

The crosslinked organosiloxane compound (B) may be represented by theaverage composition formula of Formula 2. In the above, R⁷ to R¹²represent substituents directly bound to a silicon atom, and eachindependently represent an alkoxy, a hydroxy, an epoxy or a monovalenthydrocarbon group.

Specific examples of the respective substituents may be the same as inFormula 1.

In Formula 2, at least one of R⁷ to R¹² is an alkenyl group.Particularly, the alkenyl group may be included in such an amount thatthe molar ratio (Ak/Si) of the alkenyl group (Ak) bound to a siliconatom with respect to the total silicon atoms (Si) in the compound (B) isin a range of 0.15 to 0.35, preferably in a range of 0.15 to 0.3. If themolar ratio (Ak/Si) is not less than 0.15, it is possible to optimizereactivity with the component (C) and to prevent components that havenot reacted from bleeding on the surface of the cured product. Also, ifthe molar ratio (Ak/Si) is not more than 0.35, it is possible tooptimize excellent hardness, crack resistance and thermal shockresistance of the cured product.

Also, in Formula 2, at least one of R⁷ to R¹² may be an aryl group,preferably a phenyl group. Therefore, it is possible to optimize therefractive index and hardness of the cured product. Particularly, thearyl group, preferably the phenyl group, may be included in such anamount that the molar ratio (Ar/Si) of the aryl group (Ar) with respectto the total silicon atoms (Si) in the organosiloxane compound (B) is ina range of 0.35 to 1.2, preferably in a range of 0.5 to 1.1. If themolar ratio (Ak/Si) is not less than 0.35, it is possible to optimizethe refractive index and hardness of the cured product. Also, if themolar ratio (Ak/Si) is not more than 1.2, it is possible to maintain anappropriate viscosity and thermal shock resistance of the composition.

In the above, e, f, g and h in the average composition formula ofFormula 2 may represent molar ratios of the siloxane units,respectively, and the total sum of e, f, g and h is 1; e is in a rangeof 0 to 0.5, f is in a range of 0 to 0.3, g is in a range of 0.35 to0.85, and h is in a range of 0 to 0.2. In order to maximize thehardness, crack resistance and thermal shock resistance of the curedproduct, (g+(4/3)h)/(e+2f) may be controlled to be within a range of 2to 5, preferably a range of 2 to 4, and g/(g+h) may be controlled to begreater than 0.85, preferably greater than 0.90. For example, the upperlimit of g/(g+h) may be 1.

The crosslinked organosiloxane compound (B) may have a viscosity at 25°C. of 5,000 mPa·s or more, preferably 10,000 mPa·s or more. Therefore,it is possible to maintain appropriate processability before curing andhardness after the curing.

The crosslinked organosiloxane (B) may have a molecular weight of, forexample, 1,000 to 5,000, preferably 1,000 to 4,000. If the molecularweight of the organosiloxane compound (B) is not less than 1,000, it ispossible to optimize formability of the composition before curing andhardness of the composition after curing, whereas if the molecularweight of the organosiloxane compound (B) is not more than 5,000, it ispossible to optimize properties such as viscosity.

In one embodiment, an organosiloxane compound represented by oneselected from the group consisting of the following formulas may be usedas the organosiloxane compound (B), but not limited thereto:

(ViMe₂SiO_(1/2))₃(PhSiO_(3/2))₁₀;

(ViMe₂SiO_(1/2))₂(MePhSiO_(2/2))₂(PhSiO_(3/2))₁₅;

(ViMe₂SiO_(1/2))₂(Ph₂SiO_(2/2))(PhSiO_(3/2))₈;

(ViMe₂SiO_(1/2))₃(PhSiO_(3/2))₉(SiO_(4/2));

(ViMe₂SiO_(1/2))₃(MePhSiO_(2/2))(PhSiO_(3/2))₉(SiO_(4/2));

(ViMe₂SiO_(1/2))₂(Me₂SiO_(2/2))(MePhSiO_(2/2))₂(Ph₂SiO_(2/2))(PhSiO_(3/2))₁₉(SiO_(4/2)).

In the formulae, “Vi” represents a vinyl group, “Me” represents a methylgroup, and “Ph” represents a phenyl group.

The crosslinked organosiloxane compound (B) may be prepared by methodsconventionally known in the art. For example, the organosiloxanecompound (B) may be prepared by hydrolyzing and condensing one or moreorganosilanes having a hydrolyzable group such as a halogen atom or analkoxy group. For example, the hydrolysis and condensation may beperformed in the presence of a typical acid catalyst or a base catalyst.Also, examples of the organosilanes used for the hydrolysis andcondensation may include compounds represented by R_(n)SiX_((4-n)). Inthe formula, X is a hydrolyzable group, and may include a halogen suchas chlorine or an alkoxy group, and n may be an integer ranging from 0to 3. Also in the formula, R is a substituent bound to a silicon atomand may be suitably selected in consideration of the substituent of adesired compound. Also, the linear siloxane compound may be prepared bya ring-opening reaction of cyclic siloxane in the presence of a basecatalyst. A variety of methods for preparing a siloxane compound,including the methods as described above, have been known in the art,and a desired organosiloxane compound may be prepared by a personskilled in the art by suitably using one of such methods.

The crosslinked organosiloxane compound (B) may be included in an amountof 50 parts by weight to 700 parts by weight, preferably 50 parts byweight to 500 parts by weight, relative to 100 parts by weight of thelinear organosiloxane compound included in the polymerized product (A).In this specification, the unit “part(s) by weight” means a weightratio. When the weight ratio of compound (B) is controlled to be 50parts by weight or more, it is possible to maintain excellent hardnessof the cured product, whereas when the weight ratio of compound (B) iscontrolled to be 700 parts by weight or less, it is possible to maintainexcellent crack resistance and thermal shock resistance of the curedproduct.

The curable composition includes the hydrogen siloxane compound (C)represented by Formula 3. The siloxane compound (C) includes at leastone hydrogen atom directly bound to a silicon atom. The hydrogen atommay react with the alkenyl group bound to a silicon atom in the linearorganosiloxane compound included in the polymerized product (A) and thecrosslinked organosiloxane compound (B).

In the compounds of Formula 3, R's may represent independently hydrogen,an epoxy group or a monovalent hydrocarbon group.

In the above, specific examples of the monovalent hydrocarbon group maybe the same as described above.

The siloxane compound (C) has a molecular chain, both terminal ends ofwhich are blocked by a hydrogen atom bound to a silicon atom. In thiscase, at least one of the R's included in the molecular side chain maybe hydrogen, if necessary. Particularly, a molar ratio (H/Si) of thehydrogen atom (H) bound to a silicon atom with respect to the totalsilicon atoms (Si) in the compound (C) may be in a range of 0.2 to 0.8,preferably in a range of 0.3 to 0.75. If the molar ratio is not lessthan 0.2, it is possible to maintain excellent curability of thecomposition, whereas if the molar ratio is not more than 0.8, it ispossible to maintain excellent crack resistance and thermal shockresistance of the composition.

Also, at least one of the R's in Formula 3 may be an aryl group,preferably a phenyl group. Therefore, the refractive index and hardnessof the cured product may be optimized. Specifically, the aryl group,preferably the phenyl group, may be included in such an amount that amolar ratio (Ar/Si) of the aryl group (Ar) with respect to the totalsilicon atoms (Si) in the compound (C) is in a range from 0.3 to 1, from0.3 to 0.95, from 0.3 to 0.9, from 0.3 to 0.85, from 0.3 to 0.8 or from0.4 to 0.8. By controlling the molar ratio (Ar/Si) to be 0.3 or more, itis possible to optimize a refractive index and hardness of the curedproduct. Also, by controlling the molar ratio (Ar/Si) to be 1 or less,it is possible to optimize viscosity and crack resistance of thecomposition.

In Formula 3, n may be in a range of 1 to 10, in a range of 1 to 5, in arange of 1 to 4, in a range of 1 to 3, or in a range of 1 to 2.Therefore, it is possible to maintain excellent hardness and crackresistance of the cured product.

In the above, the siloxane compound (C) may have a viscosity at 25° C.of 300 mPa·s or less, preferably 300 mPa·s or less. By controlling theviscosity of the compound (C) to fall within the ranges as describedabove, it is possible to maintain excellent processability of thecomposition and excellent hardness of the cured product.

In one embodiment, the siloxane compound (C) may also have a molecularweight of, for example, less than 1,000, preferably less than 800. Ifthe molecular weight of the compound (C) is 1,000 or more, the intensityof the cured product may be deteriorated. A lower limit of the molecularweight of the compound (C) is not particularly limited, but may be, forexample, 250.

In one embodiment, a siloxane compound that is represented by at leastone selected from the group consisting of the Formulas below may be usedas the siloxane compound (C), but is not limited thereto:

(HMe₂SiO_(1/2))₂(MePhSiO_(2/2))₂;

(HMe₂SiO_(1/2))₂(Ph₂SiO_(2/2))_(1.5);

(HMe₂SiO_(1/2))₂(MePhSiO_(2/2))_(1.5)(Ph₂SiO_(2/2))_(1.5);

(HMe₂SiO_(1/2))₂(Me₂SiO_(2/2))_(2.5)(Ph₂SiO_(2/2))_(2.5);

(HMe₂SiO_(1/2))₂(Me₂SiO_(2/2))_(1.5)(Ph₂SiO_(2/2))_(2.5);

(HMe₂SiO_(1/2))₂(HMeSiO_(1/2))(Ph₂SiO_(2/2))₂.

In the formulae, “Vi” represents a vinyl group, “Me” represents a methylgroup, and “Ph” represents a phenyl group.

In the above, a method for preparing compound (C) is not particularlylimited, and may be, for example, applied in the same manner as in thecompound (B) or the linear organosiloxane compound in the product (A).

In the above, an amount of the compound (C) may be controlled for thehydrogen atom bound to a silicon atom in compound (C) to satisfy acertain molar ratio with respect to the total alkenyl groups bound to asilicon atom included in the linear organosiloxane compound of thepolymerized product (A) and the crosslinked organosiloxane compound (B).Particularly, in one embodiment, the molar ratio (H/Ak) of the hydrogenatom (H) bound to a silicon atom included in compound (C) with respectto the total alkenyl groups (Ak) bound to a silicon atom included in thelinear organosiloxane compound of the polymerized product (A) and thecrosslinked organosiloxane compound (B) may be in a range of 0.8 to 1.2,preferably in a range of 0.85 to 1.15, and more preferably in a range of0.9 to 1.1. By controlling the molar ratio (H/Ak) as described above, acomposition, which shows excellent processability and workability beforecuring, which shows excellent crack resistance, hardness, thermal shockresistance and adhesive strength after curing, and which preventsturbidity and tackiness on the surface from being generated under severeconditions may be provided.

As a weight ratio, the siloxane compound (C) may be included in anamount of 50 parts by weight to 500 parts by weight, preferably in arange of 50 parts by weight to 400 parts by weight, relative to 100parts by weight of the linear organosiloxane compound in the polymerizedproduct (A).

Considering the refractive index and hardness, all of the linearorganosiloxane compound of the product (A), crosslinked organosiloxanecompound (B) and compound (C) may include at least one aryl group thatis bound to a silicon atom thereof respectively. Examples of the arylgroup may include a phenyl group. In cases where all of the abovecompounds include at least one aryl group, the molar ratio (Ar/Si) ofthe total aryl groups (Ar) bound to a silicon atom included in the abovecompounds with respect to the total silicon atoms (Si) included in theabove compounds may be preferably greater than 0.3 and 1.2 or less, andmore preferably may be in a range of 0.4 to 1.2. By controlling themolar ratio to exceed 0.3, it is possible to maintain excellent hardnessand refractive index of the cured product. Also, by controlling themolar ratio to be 1.2 or less, the viscosity of the composition may beeffectively controlled.

In the case where all of the above compounds include at least one arylgroup, it is preferable for the curable composition to satisfy Equations1 and 2:

|X _((A)) −X _((B))|<0.4  [Equation 1]

|X _((B)) −X _((C))|<0.4  [Equation 2]

wherein X_((A)) represents a molar ratio of an aryl group bound to thesilicon atoms included in the linear organosiloxane compound in theproduct (A) with respect to the total silicon atoms in the linearorganosiloxane compound in the product (A), X_((B)) represents a molarratio of an aryl group bound to the silicon atoms included in thecompound (B) with respect to the total silicon atoms in the compound(B), and X_((C)) represents a molar ratio of an aryl group bound to thesilicon atoms included in the compound (C) with respect to the totalsilicon atoms in the compound (C).

In Equations 1 and 2, |X_((A))−X_((B))| and |X_((B))−X_((C))| mean anabsolute value of the difference between X_((A)) and X_((B)) and anabsolute value of the difference between X_((B)) and X_((C)),respectively. Here, each of the absolute values may preferably be lessthan 0.35. Also, the lower limits of the absolute values are notparticularly limited.

If a molar ratio of the aryl group satisfies the requirements ofEquations 1 and 2, it is possible to provide a composition showingexcellent compatibility between components which constitute thecomposition and have excellent processability and workability beforecuring, and to provide a composition which may show excellent refractiveindex, optical transmittance and hardness after curing.

The curable composition may further include a hydrosilylation catalyst.The hydrosilylation catalyst may be used to facilitate the reaction ofthe hydrogen atom bound to a silicon atom with the alkenyl groups. Kindsof the hydrosilylation catalyst that may be used herein are notparticularly limited, and any hydrosilylation catalysts that are knownin the art may be used. Examples of such a catalyst may include aplatinum, palladium or rhodium catalyst. In one embodiment, the platinumcatalyst may be used in consideration of catalytic efficiency, etc.Examples of such a catalyst may include, but are not limited to,chloroplatinic acid, platinum tetrachloride, an olefin complex ofplatinum, an alkenyl siloxane complex of platinum or a carbonyl complexof platinum, etc.

In the above, an amount of the hydrosilylation catalyst is notparticularly limited, as long as the hydrosilylation catalyst is presentin a so-called catalytic amount, i.e. an amount in which hydrosilylationcatalyst may act as a catalyst. Typically, the hydrosilylation catalystmay be included in an amount of 0.1 ppm to 500 ppm, preferably 0.2 ppmto 100 ppm, based on the atomic weight of platinum, palladium orrhodium.

Also, the curable composition may further include a tackifier in orderto further improve adhesive strength to various bases. The tackifier mayimprove self-adhesive strength to a composition or cured product, andparticularly may improve self-adhesive strength to a metal and anorganic resin.

Examples of the tackifier usable herein may include, but are not limitedto, a silane having at least one functional group, preferably at leasttwo functional groups, selected from the group consisting of an alkenylgroup such as a vinyl group, a (meth)acryloyloxy group, a hydrosilylgroup (a SiH group), an epoxy group, an alkoxy group, an alkoxysilylgroup, a carbonyl group and a phenyl group; or an organic siliconcompound such as cyclic or linear siloxanes having 2 to 30 siliconatoms, preferably 4 to 20 silicon atoms. The tackifier may be used aloneor in combinations thereof.

If the tackifier is included in the composition, an amount of thetackifier may be in a range of 0.1 parts by weight to 20 parts byweight, relative to 100 parts by weight of the linear organosiloxanecompound of the polymerized product (A), but may be suitably varied inconsideration of the desired improvement of the adhesive strength.

Along with the components as described above, the curable compositionmay optionally further include at least one additive selected from thegroup consisting of a reaction inhibitor such as 2-methyl-3-butyn-2-ol,2-phenyl-3-1-butin-2-ol, 3-methyl-3-penten-1-in,3,5-dimethyl-3-hexen-1-in,1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane orethynylcyclohexane; an inorganic filler such as silica, alumina,zirconia or titania; carbon-functional silane and partially hydrolyzedcondensates thereof or a siloxane compound having an epoxy group and/oran alkoxysilyl group; a thixotropic agent such as aerosolized silicausable in combination with polyether; a conductivity-providing agentsuch as metal powder including silver, copper or aluminum, or variouscarbon materials; and a color control agent such as a pigment or a dye.

The present application also relates to a semiconductor device thatincludes a semiconductor element encapsulated by an encapsulant thatincludes the curable composition as described above in a cured state.

Examples of the semiconductor element which may be encapsulated by thecurable composition may include semiconductor elements used in a diode,a transistor, a thyristor, a solid image pickup device, an integral ICand a hybrid IC. Additionally, exemplary examples of the semiconductordevice may include a diode, a transistor, a thyristor, a photocoupler,CCD, an integral IC, a hybrid IC, LSI, VLSI and a light-emitting diode(LED).

In one embodiment, the semiconductor device may be a light-emittingdiode that includes a light-emitting element that is encapsulated by anencapsulant that includes the curable composition as described above ina cured state.

Kinds of the light-emitting element usable herein are not particularlylimited. For example, a light-emitting element formed by laminating asemiconductor material on a substrate may be used. In this case,examples of the semiconductor material may include, but are not limitedto, GaAs, GaP, GaAlAs, GaAsP, AlGaInP, GaN, InN, AlN, InGalN or SiC.Also, examples of the substrate used herein may include sapphire,spinel, SiC, Si, ZnO or GaN single crystals.

In one embodiment, a buffer layer may also be formed between thesubstrate and the semiconductor material, if necessary. In this case, aGaN or AlN may be used as the buffer layer. A method of laminating asemiconductor material on a substrate is not particularly limited, butmay include, for example, an MOCVD, HDVPE or a liquid phase epitaxymethod. In the above, a structure of the light-emitting element mayinclude, for example, a monojunction structure, a heterojunctionstructure and a double heterojunction structure having an MIS junction,a PN junction, or a PIN junction. Also, the light-emitting element maybe formed in a single or multiple quantum well structure.

In one embodiment, an emission wavelength of the light-emitting elementmay be, for example, in a range of 250 nm to 550 nm, preferably in arange of 300 nm to 500 nm, and more preferably in a range of 330 nm to470 nm. The emission wavelength represents a peak emission wavelength.When the emission wavelength of the light-emitting element falls withinthis wavelength, it is possible to obtain a white light-emitting elementhaving a longer life span and showing high energy efficiency and colorreproduction.

The light-emitting diode may be manufactured by encapsulating alight-emitting element, particularly a light-emitting element having anemission wavelength of 250 nm to 550 nm, with an encapsulating materialincluding the curable composition as described above. In this case, theencapsulation of the light-emitting element may be performed using onlythe curable composition as described above, and may be performed incombination with another encapsulant, if necessary. When at least twoencapsulants are used together, a light-emitting element may beencapsulated with the curable composition as described above, followedby encapsulating the primarily encapsulated light-emitting element withanother encapsulant, or may be encapsulated with another encapsulant,followed by encapsulating the primarily encapsulated light-emittingelement with the curable composition as described above. The otherencapsulant which may be used herein may include an epoxy resin, asilicone resin, an acryl resin, a urea resin, an imide resin or glass.

For example, a method of encapsulating a light-emitting element with thecurable composition as described above includes a method of firstinjecting the curable composition as described above into a mold-typecast, soaking a lead frame, in which a light-emitting element is fixed,in the curable composition as described above and curing the curablecomposition; a method of injecting the curable composition as describedabove into a cast to which a light-emitting element is inserted andcuring the curable composition; etc. In this case, examples of themethod of injecting the curable composition may include injection usinga dispenser, transfer molding, injection molding, etc. Also, otherencapsulation methods used herein may include a method of applying thecurable composition as described above onto a light-emitting device andcuring the curable composition by means of a dropping, stencil printing,screen printing or a mask process, a method of injecting the curablecomposition in a cup having a light-emitting element disposed thereinusing a dispenser and curing the curable composition, etc. Also, thecurable composition as described above may be used as a die-bondmaterial for fixing a light-emitting element in a lead terminal or apackage, a passivation film on a light-emitting device, a packagesubstrate, etc.

The method of curing the curable composition as described above is notparticularly limited, but may be performed, for example, by heating thecomposition at a temperature of 60° C. to 200° C. for 10 minutes to 5hours, and be optionally performed by undergoing at least two steps ofthe curing at conditions of suitable temperature and time.

A shape of an encapsulated portion is not particularly limited, but maybe formed in a shell-type lens, planar or thin-film shape.

In one embodiment, performance of the light-emitting element may also beimproved using additional conventionally known methods. Methods ofimproving the performance may, for example, include a method ofinstalling a light reflective layer or a light-concentrating layer at arear surface of a light-emitting element, a method of forming acomplementarily colored portion at a bottom of a light-emitting element,a method of installing a layer for absorbing light of a wavelengthshorter than a main emission peak wavelength on a light-emittingelement, a method of encapsulating a light-emitting element and furthermolding the light-emitting element using a hard material, a method offixing a light-emitting diode through a through hole, a method ofconnecting a light-emitting element to a lead member using a flip chipinterconnection, thereby extracting light in a direction of a substrate,etc.

The light-emitting diode may be, for example, effectively used as alight source such as a backlight unit of a liquid crystal display device(LCD), various sensors, a printer, or a photocopier, a light source foran automobile dashboard, a traffic light, a pilot lamp, a displaydevice, a light source for a planar luminous body, displays, decorationsor various lights.

Advantageous Effects

The curable composition shows excellent processability and workability.Also, the curable composition shows excellent crack resistance, thermalshock resistance and adhesive strength and also has excellentreliability and long-term reliability under high-temperature and/orhigh-moisture conditions. In addition, the curable composition mayprovide a cured product, which is capable of preventing turbidity frombeing generated, and which is capable of preventing tackiness on thesurface from being generated, and therefore surface stickiness may beprevented.

BEST MODE

Hereinafter, the present application will be described in further detailreferring to Examples designed according to the present application andComparative Examples that are not designed according to the presentapplication; however, the present application is not limited toExamples.

In Examples, “Vi” represents a vinyl group, “Ph” represents a phenylgroup, “Me” represents a methyl group, and “Ep” represents an epoxygroup.

1. Measurement of Optical Transmittance

In Examples and Comparative Examples, optical transmittance of curedproducts was evaluated, as follows. First, a prepared composition wasinjected between two glass plates which were arranged to be spaced at adistance of approximately 1 mm apart from each other, and cured at aconstant temperature of 150° C. for 1 hour to prepare a 1 mm-thick testsample. Then, the test sample was measured at room temperature foroptical transmittance in a thickness direction with respect to awavelength range of 450 nm using a UV-VIS spectrometer, and evaluatedaccording to the following criteria.

<Criteria for Evaluation of Optical Transmittance>

◯: Optical transmittance of 98.5% or more

x: Optical transmittance of less than 98.5%

2. Evaluation of Surface Stickiness

A curable composition was injected into a mold, and cured at a constanttemperature of 150° C. for 1 hour. Then, surface stickiness wasevaluated according to the following criteria by contacting a surface ofthe resulting cured product with hands.

<Criteria for Evaluation of Surface Stickiness>

◯: Surface is hardly sticky

Δ: Surface is slightly sticky

x: Surface is highly sticky

3. Evaluation of Device Properties

A 5630 LED package prepared from polyphthalamide (PPA) was used toevaluate device properties. More particularly, a curable composition wasdispensed into a polyphthalamide cup, and cured at a constanttemperature of 60° C. for 30 minutes, and then at a constant temperatureof 150° C. for 1 hour to prepare a surface-mounted LED. Then, the LEDwas evaluated for thermal shock and long-term reliability under thehigh-temperature/high-moisture conditions, as follows.

<Criteria for Evaluation of Thermal Shock>

One cycle, in which the prepared surface-mounted LED was left at aconstant temperature of −40° C. for 30 minutes, and then was left at aconstant temperature of 100° C. for 30 minutes, was repeated 10 times.Then, the surface-mounted LED was cooled at room temperature, andevaluated for a peeling state to determine the thermal shock resistance(Total 10 surface-mounted LED's were prepared in each of Examples andComparative Examples, and evaluated for a peeling state).

<Long-Term Reliability at High-Temperature/High-Moisture Conditions>

The prepared surface-mounted LED was operated for 100 hours underconstant conditions of a temperature of 85° C. and relative moisture of85% while applying an electric current of 60 mA to the LED. After thecompletion of the operation, a luminance of the LED was then measured tocalculate reduction in luminance with respect to the initial luminance,and the reliability was evaluated according to the following criteria.

<Evaluation Criteria>

◯: the case where Luminance is reduced by 10% or less with respect toinitial luminance

x: the case where Luminance is reduced by 10% or more with respect toinitial luminance

4. Evaluation of the Amount of the Low Molecular Weight Cyclic Compounds

The amount of the low molecular weight cyclic compounds in thepolymerized product was measured by GPC device available from Water Co.

MODE FOR APPLICATION Preparation Example 1

50.0 g of octamethylcyclotetrasiloxane, 133.7 g ofoctaphenylcyclotetrasiloxane, 36.7 g oftetramethyltetraphenylcyclotetrasiloxane and 12.6 g ofdivinyltetramethyldisiloxane were mixed, and then 0.75 mL of TMAH(tetramethylammonium hydroxide) was added thereto. Then, a ring openingpolymerization reaction was performed in a temperature of 110° C. for 15hours. After the reaction, a ring opening polymerization reactionproduct including a linear organosiloxane compound represented byFormula 1 was obtained. Then, the low molecular weight cyclic compoundshaving the molecular weight of 800 were eliminated via a conventionalpurification process from the ring opening polymerization reactionproduct so as for the amount of the cyclic compounds to be 13 weight %.

[ViMe₂SiO_(1/2)]₂[Me₂SiO_(2/2)]₉[Ph₂SiO_(2/2)]₁₀[PhMeSiO_(2/2)]₄  [Formula1]

Preparation Example 2

50.0 g of octamethylcyclotetrasiloxane, 100.3 g ofoctaphenylcyclotetrasiloxane, 64.3 g oftetramethyltetraphenylcyclotetrasiloxane and 3.1 g ofdivinyltetramethyldisiloxane were mixed, and then 0.70 mL of TMAH(tetramethylammonium hydroxide) was added thereto. Then, a ring openingpolymerization reaction was performed in a temperature of 110° C. for 15hours. After the reaction, a ring opening polymerization reactionproduct including a linear organosiloxane compound represented byFormula 5 was obtained. Then, the low molecular weight cyclic compoundswere eliminated via a conventional purification process from the ringopening polymerization reaction product so as for the amount of thecyclic compounds to be 13 weight %.

[ViMe₂SiO_(1/2)]₂[Me₂SiO_(2/2)]₄₀[Ph₂SiO_(2/2)]₃₀[PhMeSiO_(2/2)]₂₈  [Formula5]

Preparation Example 3

8.7 g of tetravinyltetramethylcyclotetrasiloxane, 92.0 g oftetramethyltetraphenylcyclotetrasiloxane and 6.3 g ofdivinyltetramethyldisiloxane were mixed, and then 0.3 mL of TMAH(tetramethylammonium hydroxide) was added thereto. Then, a ring openingpolymerization reaction was performed in a temperature of 90° C. for 15hours. After the reaction, a ring opening polymerization reactionproduct including a linear organosiloxane compound represented byFormula 6 was obtained. Then, the low molecular weight cyclic compoundswere eliminated via a conventional purification process from the ringopening polymerization reaction product so as for the amount of thecyclic compounds to be 13 weight %.

[ViMe₂SiO_(1/2)]₂[ViMeSiO_(2/2)]₃[PhMeSiO_(2/2)]₂₀  [Formula 6]

Preparation Example 4

40.0 g of octamethylcyclotetrasiloxane, 107.0 g ofoctaphenylcyclotetrasiloxane, 73.5 g oftetramethyltetraphenylcyclotetrasiloxane and 2.5 g ofdivinyltetramethyldisiloxane were mixed, and then 0.7 mL of TMAH(tetramethylammonium hydroxide) was added thereto. Then, a ring openingpolymerization reaction was performed in a temperature of 110° C. for 15hours. After the reaction, a ring opening polymerization reactionproduct including a linear organosiloxane compound represented byFormula 7 was obtained. Then, the low molecular weight cyclic compoundswere eliminated via a conventional purification process from the ringopening polymerization reaction product so as for the amount of thecyclic compounds to be 13 weight %.

[ViMe₂SiO_(1/2)]₂[Me₂SiO_(2/2)]₅₀[Ph₂SiO_(2/2)]₅₀[PhMeSiO_(2/2)]₅₀  [Formula7]

Preparation Example 5

17.1 g of tetravinyltetramethylcyclotetrasiloxane, 90.0 g oftetramethyltetraphenylcyclotetrasiloxane and 6.2 g ofdivinyltetramethyldisiloxane were mixed, and then 0.4 mL of TMAH(tetramethylammonium hydroxide) was added thereto. Then, a ring openingpolymerization reaction was performed in a temperature of 90° C. for 15hours. After the reaction, a ring opening polymerization reactionproduct including a linear organosiloxane compound represented byFormula 8 was obtained. Then, the low molecular weight cyclic compoundswere eliminated via a conventional purification process from the ringopening polymerization reaction product so as for the amount of thecyclic compounds to be 13 weight %.

[ViMe₂SiO_(1/2)]₂[ViMeSiO_(2/2)]₆[PhMeSiO_(2/2)]₂₀  [Formula 8]

Preparation Example 6

A ring opening polymerization reaction product including the linearorganosiloxane compound represented by Formula 1 was prepared in thesame manner as in Preparation Example 1 except that the purificationprocess was performed so as for the amount of the cyclic compounds to be6 weight %.

Preparation Example 7

A ring opening polymerization reaction product including the linearorganosiloxane compound represented by Formula 5 was prepared in thesame manner as in Preparation Example 2 except that the purificationprocess was performed so as for the amount of the cyclic compounds to be6 weight %.

Preparation Example 8

A ring opening polymerization reaction product including the linearorganosiloxane compound represented by Formula 6 was prepared in thesame manner as in Preparation Example 3 except that the purificationprocess was performed so as for the amount of the cyclic compounds to be6 weight %.

Example 1

The ring opening polymerization reaction product prepared in thepreparation example 1 was mixed with the compounds which wererepresented by the Formulas 2 to 4 as described below. The compounds ofFormulas 2 to 4 were prepared by methods conventionally known to aperson skilled in the art. Therefore, a mixture including a linearorganosiloxane compound (Formula 1; molar ratio (hereinafter, referredto as “Ak/Si”) of an alkenyl group (Vi) bound to a silicon atom withrespect to the total silicon atoms: 0.08), a crosslinked organosiloxanecompound (Formula 2; Ak/Si: 0.154) and a hydrogen siloxane compound(Formula 3; molar ratio (hereinafter, referred to as “H/Si”) of ahydrogen atom bound to a silicon atom with respect to the total siliconatoms: 0.667), and an tackifier (Formula 4) was obtained. The mixturewas prepared so that 100 g of the linear organosiloxane compound(Formula 1), 50 g of the crosslinked organosiloxane compound (Formula2), 20.7 g of the hydrogen siloxane compound (Formula 3) and 3.5 g ofthe tackifier (Formula 4) might be presented (in such an amount that themolar ratio (hereinafter, referred to as “H/Ak”) of a hydrogen atombound to a silicon atom in the hydrogen siloxane compound with respectto an alkenyl group (Vi) bound to a silicon atom in the linear andcrosslinked organosiloxane compound is 1.0). Then, a catalyst(platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane) was mixed insuch an amount that the content of Pt(0) in the resulting mixture was 10ppm, homogeneously mixed, and degassed to prepare a curable composition.

[ViMe₂SiO_(1/2)]₂[Me₂SiO_(2/2)]₉[Ph₂SiO_(2/2)]₁₀[PhMeSiO_(2/2)]₄  [Formula1]

[ViMeSiO_(2/2)][PhMeSiO_(2/2)][PhSiO_(3/2)]₁₀[ViMe₂SiO_(1/2)]  [Formula2]

[HMe₂SiO_(1/2)]₂[Ph₂SiO_(2/2)][Formula 3]

[ViMe₂SiO_(1/2)]₂[EpSiO_(3/2)]₂[PhMeSiO_(2/2)]₁₀  [Formula 4]

Example 2

A curable composition was prepared in the same manner as in Example 1,except that the mixture was prepared so that 100 g of the linearorganosiloxane compound of Formula 1, 100 g of the crosslinkedorganosiloxane compound of Formula 2, 31.2 g of the hydrogen siloxanecompound of Formula 3, and 4.7 g of the tackifier of Formula 4 might bemixed together (in such an amount that the molar ratio H/Ak was 1.0).

Example 3

A curable composition was prepared in the same manner as in Example 1,except that the mixture was prepared so that 100 g of the linearorganosiloxane compound of Formula 1, 300 g of the crosslinkedorganosiloxane compound of Formula 2, 73.3 g of the hydrogen siloxanecompound of Formula 3, and 9.7 g of the tackifier of Formula 4 might bemixed together (in such an amount that the molar ratio H/Ak was 1.0).

Example 4

A curable composition was prepared in the same manner as in Example 1,except that the mixture was prepared so that 100 g of the linearorganosiloxane compound of Formula 1, 700 g of the crosslinkedorganosiloxane compound of Formula 2, 157.2 g of the hydrogen siloxanecompound of Formula 3, and 19.6 g of the tackifier of Formula 4 might bemixed together (in such an amount that the molar ratio H/Ak was 1.0).

Example 5

A curable composition was prepared in the same manner as in Example 1,except that the reaction product of Preparation Example 2 was usedinstead of the reaction product of Preparation Example 1, and themixture was prepared so that 100 g of a compound (Ak/Si: 0.02) which wasrepresented by the Formula 5 and which was a linear organosiloxanecompound, 50 g of the crosslinked organosiloxane compound of Formula 2,13.5 g of the hydrogen siloxane compound of Formula 3, and 3.4 g of thetackifier of Formula 4 might be mixed together (in such an amount thatthe molar ratio H/Ak was 1.0).

[ViMe₂SiO_(1/2)]₂[Me₂SiO_(2/2)]₄₀[Ph₂SiO_(2/2)]₃₀[PhMeSiO_(2/2)]₂₈  [Formula5]

Example 6

A curable composition was prepared in the same manner as in Example 1,except that the mixture was prepared so that 100 g of the linearorganosiloxane compound of Formula 5, 100 g of the crosslinkedorganosiloxane compound of Formula 2, 23.9 g of the hydrogen siloxanecompound of Formula 3, and 4.6 g of the tackifier of Formula 4 might bemixed together (in such an amount that the molar ratio H/Ak was 1.0).

Example 7

A curable composition was prepared in the same manner as in Example 1,except that the mixture was prepared so that 100 g of the linearorganosiloxane compound of Formula 5, 300 g of the crosslinkedorganosiloxane compound of Formula 2, 64.1 g of the hydrogen siloxanecompound of Formula 3, and 9.5 g of the tackifier of Formula 4 might bemixed together (in such an amount that the molar ratio H/Ak was 1.0).

Example 8

A curable composition was prepared in the same manner as in Example 1,except that the mixture was prepared so that 100 g of the linearorganosiloxane compound of Formula 5, 700 g of the crosslinkedorganosiloxane compound of Formula 2, 145.2 g of the hydrogen siloxanecompound of Formula 3, and 19.2 g of the tackifier of Formula 4 might bemixed together (in such an amount that the molar ratio H/Ak was 1.0).

Example 9

A curable composition was prepared in the same manner as in Example 1,except that the reaction product of Preparation Example 3 was usedinstead of the reaction product of Preparation Example 1, and themixture was prepared so that 100 g of a compound (Ak/Si: 0.2)represented by Formula 6 and which was a linear organosiloxane compound,50 g of the crosslinked organosiloxane compound of Formula 2, 37.2 g ofthe hydrogen siloxane compound of Formula 3, and 3.9 g of the tackifierof Formula 4 might be mixed together (in such an amount that the molarratio H/Ak was 1.0).

[ViMe₂SiO_(1/2)]₂[ViMeSiO_(2/2)]₃[PhMeSiO_(2/2)]₂₀  [Formula 6]

Example 10

A curable composition was prepared in the same manner as in Example 1,except that the mixture was prepared so that 100 g of the linearorganosiloxane compound of Formula 6, 100 g of the crosslinkedorganosiloxane compound of Formula 2, 47.8 g of the hydrogen siloxanecompound of Formula 3, and 5.1 g of the tackifier of Formula 4 might bemixed together (in such an amount that the molar ratio H/Ak was 1.0).

Example 11

A curable composition was prepared in the same manner as in Example 1,except that the mixture was prepared so that 100 g of the linearorganosiloxane compound of Formula 6, 300 g of the crosslinkedorganosiloxane compound of Formula 2, 89.7 g of the hydrogen siloxanecompound of Formula 3, and 10.0 g of the tackifier of Formula 4 might bemixed together (in such an amount that the molar ratio H/Ak was 1.0).

Example 12

A curable composition was prepared in the same manner as in Example 1,except that the mixture was prepared so that 100 g of the linearorganosiloxane compound of Formula 6, 700 g of the crosslinkedorganosiloxane compound of Formula 2, 173.6 g of the hydrogen siloxanecompound of Formula 3, and 19.8 g of the tackifier of Formula 4 might bemixed together (in such an amount that the molar ratio H/Ak was 1.0).

Example 13

A curable composition was prepared in the same manner as in Example 1,except that the reaction product of Preparation Example 6 was usedinstead of the reaction product of Preparation Example 1.

Example 14

A curable composition was prepared in the same manner as in Example 5,except that the reaction product of Preparation Example 7 was usedinstead of the reaction product of Preparation Example 2.

Example 15

A curable composition was prepared in the same manner as in Example 9,except that the reaction product of Preparation Example 8 was usedinstead of the reaction product of Preparation Example 3.

Comparative Example 1

A curable composition was prepared in the same manner as in Example 1,except that the reaction product of Preparation Example 4 was usedinstead of the reaction product of Preparation Example 1, and themixture was prepared so that 100 g of a compound (Ak/Si: 0.013)represented by Formula 7 and which was a linear organosiloxane compound,300 g of the crosslinked organosiloxane compound of Formula 2, 65.0 g ofthe hydrogen siloxane compound of Formula 3, and 9.5 g of the tackifierof Formula 4 might be mixed together (in such an amount that the molarratio H/Ak was 1.0).

[ViMe₂SiO_(1/2)]₂[Me₂SiO_(2/2)]₅₀[Ph₂SiO_(2/2)]₅₀[PhMeSiO_(2/2)]₅₀  [Formula7]

Comparative Example 2

A curable composition was prepared in the same manner as in Example 1,except that the reaction product of Preparation Example 5 was usedinstead of the reaction product of Preparation Example 1, and themixture was prepared so that 100 g of a compound (Ak/Si: 0.29)represented by Formula 8 that was a linear organosiloxane compound, 300g of the crosslinked organosiloxane compound of Formula 2, 102.5 g ofthe hydrogen siloxane compound of Formula 3, and 10.2 g of the tackifierof Formula 4 might be mixed together (in such an amount that the molarratio H/Ak was 1.0).

[ViMe₂SiO_(1/2)]₂[ViMeSiO_(2/2)]₆[PhMeSiO_(2/2)]₂₀  [Formula 8]

Comparative Example 3

A curable composition was prepared in the same manner as in Example 1,except that the mixture was prepared so that 100 g of the linearorganosiloxane compound of Formula 1, 45 g of the crosslinkedorganosiloxane compound of Formula 2, 19.8 g of the hydrogen siloxanecompound of Formula 3, and 3.4 g of the tackifier of Formula 4 might bemixed together (in such an amount that the molar ratio H/Ak was 1.0).

Comparative Example 4

A curable composition was prepared in the same manner as in Example 1,except that the mixture was prepared so that 100 g of the linearorganosiloxane compound of Formula 1, 750 g of the crosslinkedorganosiloxane compound of Formula 2, 167.8 g of the hydrogen siloxanecompound of Formula 3, and 21.0 g of the tackifier of Formula 4 might bemixed together (in such an amount that the molar ratio H/Ak was 1.0).

Comparative Example 5

A curable composition was prepared in the same manner as in Example 1,except that the mixture was prepared so that 100 g of the linearorganosiloxane compound of Formula 1, 300 g of the crosslinkedorganosiloxane compound of Formula 2, 40.0 g of the hydrogen siloxanecompound of Formula 3, and 9.0 g of the tackifier of Formula 4 might bemixed together (in such an amount that the molar ratio H/Ak was 0.6).

Comparative Example 6

A curable composition was prepared in the same manner as in Example 1,except that the mixture was prepared so that 100 g of the linearorganosiloxane compound of Formula 1, 300 g of the crosslinkedorganosiloxane compound of Formula 2, 11.5 g of the crosslinkedorganosiloxane compound of Formula 3, and 150.0 g of the hydrogensiloxane compound of Formula 4 might be mixed together (in such anamount that the molar ratio H/Ak was 1.4).

The evaluation results of the curable compositions are summarized andlisted in the following Table 1.

TABLE 1 High- temperature/ Thermal High- Optical Surface Shock moistureTransmittance Stickiness Resistance Reliability Examples 1 ∘ ∘ 2/10 ∘ 2∘ ∘ 1/10 ∘ 3 ∘ ∘ 0/10 ∘ 4 ∘ ∘ 1/10 ∘ 5 ∘ ∘ 2/10 ∘ 6 ∘ ∘ 1/10 ∘ 7 ∘ ∘0/10 ∘ 8 ∘ ∘ 1/10 ∘ 9 ∘ ∘ 2/10 ∘ 10 ∘ ∘ 0/10 ∘ 11 ∘ ∘ 0/10 ∘ 12 ∘ ∘ 0/10∘ 13 ∘ ∘ 0/10 ∘ 14 ∘ ∘ 0/10 ∘ 15 ∘ ∘ 0/10 ∘ Comparative 1 ∘ Δ 7/10 xExamples 2 ∘ ∘ 7/10 x 3 ∘ x 10/10  x 4 ∘ ∘ 10/10  x 5 ∘ ∘ 9/10 x 6 ∘ ∘9/10 x

As seen from Table 1, it was revealed that the curable compositions ofExamples designed according to the present application showed excellentoptical transmittance after curing without causing surface stickiness.Also, it was revealed that the curable compositions of Examples hadexcellent thermal shock resistance and showed excellent results in thelong-term reliability test under the high-temperature/high-moistureconditions.

Meanwhile, although the other conditions were within the scope of thepresent application, in the cases of Comparative Examples 1 and 2 inwhich a linear organosiloxane compound had a low or high molar ratioAk/Si, the composition showed seriously deteriorated thermal shockresistance and reliability. Also, in the cases of Comparative Examples 3and 4 in which a weight ratio of the crosslinked organosiloxane compoundto the linear organosiloxane compound was low or high, the compositionshowed seriously deteriorated thermal shock resistance and reliability,and surface stickiness was particularly present in the composition ofComparative Example 3. Also, it was confirmed that the thermal shockresistance and reliability of the composition were seriouslydeteriorated in the cases of Comparative Examples 5 and 6 in which themolar ratio H/Ak was low or high.

1. A curable composition that comprises: (A) a polymerized productcomprising a linear organosiloxane compound, which is represented by anaverage composition formula of Formula 1 and, of which a molar ratio ofan alkenyl group bound to a silicon atom with respect to the totalsilicon atoms ranges from 0.02 to 0.2; (B) a crosslinked organosiloxanecompound, which is represented by an average composition formula ofFormula 2, and of which a molar ratio of an alkenyl group bound to asilicon atom with respect to the total silicon atoms ranges from 0.15 to0.35; and (C) a hydrogen siloxane compound, which is represented byFormula 3, and of which a molar ratio of a hydrogen atom bound to asilicon atom with respect to the total silicon atoms ranges from 0.2 to0.8, the crosslinked organosiloxane compound being comprised in a weightratio of 50 parts by weight to 700 parts by weight relative to 100 partsby weight of the linear organosiloxane compound, and a molar ratio of ahydrogen atom bound to a silicon atom in the siloxane compound withrespect to an alkenyl group bound to a silicon atom in the linear andcrosslinked organosiloxane compounds ranging from 0.8 to 1.2:(R¹R²R³SiO_(1/2))_(a)(R⁴R⁵SiO_(2/2))_(b)(R⁶SiO_(3/2))_(c)(SiO_(4/2))_(d)  [Formula1](R⁷R⁸R⁹SiO_(1/2))_(e)(R¹⁰R¹¹SiO)_(f)(R¹²SiO_(3/2))_(g)(SiO_(4/2))_(h)  [Formula2]

wherein R¹ to R¹² independently represent an alkoxy group, a hydroxygroup, an epoxy group or a monovalent hydrocarbon group, with theprovision that at least one of R¹ to R⁶ is an alkenyl group and at leastone of R⁷ to R¹² is an alkenyl group; R's independently representhydrogen, an epoxy group or a monovalent hydrocarbon group; a is in arange of 0 to 0.5, b is in a range of 0.5 to 0.98, c is in a range of 0to 0.2, d is in a range of 0 to 0.1, e is in a range of 0 to 0.5, f isin a range of 0 to 0.3, g is in a range of 0.3 to 0.85, h is in a rangeof 0 to 0.2, n is in a range of 1 to 10, with the provision that a+b+c+dis 1 and e+f+g+h is
 1. 2. The curable composition of claim 1, whereinthe organosiloxane compound in the polymerized product (A) has a molarratio of an alkenyl group bound to a silicon atom with respect to thetotal silicon atoms in the organosiloxane compound in the polymerizedproduct (A) ranging from 0.02 to 0.15.
 3. The curable composition ofclaim 1, wherein the organosiloxane compound in the polymerized product(A) comprises at least one aryl group that is bound to a silicon atom.4. The curable composition of claim 3, wherein the organosiloxanecompound in the polymerized product (A) has a molar ratio of an arylgroup bound to a silicon atom with respect to the total silicon atoms inthe compound in the polymerized product (A) ranging from 0.3 to 1.3. 5.The curable composition of claim 1, wherein the organosiloxane compoundin the polymerized product (A) has a weight average molecular weight of1,000 to 50,000.
 6. The curable composition of claim 1, wherein theorganosiloxane compound in the polymerized product (A) comprises atleast one difunctional siloxane unit represented by Formula 5 and atleast one difunctional siloxane unit represented by Formula 6, andwherein the molar ratio of the difunctional siloxane unit of Formula 6with respect to the total difunctional siloxane units in theorganosiloxane compound in the polymerized product (A) is 30% or more:(R¹³R¹⁴SiO)  [Formula 5](R¹⁵R¹⁶SiO)  [Formula 6] wherein R¹³ and R¹⁴ independently represent analkyl group, and R¹⁵ and R¹⁶ independently represent an aryl group. 7.The curable composition of claim 1, wherein the polymerized productcomprises cyclic compounds having a weight average molecular weight ofnot more than 800 in an amount of 10 weight % or less.
 8. The curablecomposition of claim 7, wherein the cyclic compound is represented byFormula 7:

wherein R^(e) and R^(f) independently represent an alkyl group, R^(g)and R^(h) independently represent an aryl group, q is 0 or a positivenumber, r is 0 or a positive number, and g+r is in a range from 3 to 10.9. The curable composition of claim 1, wherein the polymerized productis a ring-opening polymerization reaction product of a mixturecomprising a compound represented by Formula 8:

wherein R^(a) and R^(b) independently represent an alkoxy group, ahydroxy group, an epoxy group or a monovalent hydrocarbon group, and pis in a range from 3 to
 10. 10. The curable composition of claim 9,wherein the polymerized product is a ring-opening polymerization of amixture comprising a compound represented by Formula 8, in which both ofR^(a) and R^(b) are alkyl groups, and a compound represented by Formula4, in which both of R^(a) and R^(b) are aryl groups.
 11. The curablecomposition of claim 1, wherein the organosiloxane compound (B) has amolar ratio of an alkenyl group bound to a silicon atom with respect tothe total silicon atoms in the compound (B) ranging from 0.15 to 0.3.12. The curable composition of claim 1, wherein the organosiloxanecompound (B) comprises at least one aryl group that is bound to asilicon atom.
 13. The curable composition of claim 12, wherein theorganosiloxane compound (B) has a molar ratio of an aryl group bound toa silicon atom with respect to the total silicon atoms in the compound(B) ranging from 0.35 to 1.2.
 14. The curable composition of claim 1,wherein the organosiloxane compound (B) has a weight average molecularweight of 1,000 to 5,000.
 15. The curable composition of claim 1,wherein the hydrogen siloxane compound (C) has a molar ratio of ahydrogen atom bound to a silicon atom with respect to the total siliconatoms in the compound (C) ranging from 0.3 to 0.75.
 16. The curablecomposition of claim 1, wherein the hydrogen siloxane compound (C)comprises at least one aryl group that is bound to a silicon atom. 17.The curable composition of claim 12, wherein the siloxane compound (C)has a molar ratio of an aryl group bound to a silicon atom with respectto the total silicon atoms in the compound (C) ranging from 0.3 to 1.18. The curable composition of claim 1, wherein the hydrogen siloxanecompound (C) has a molar ratio of a hydrogen atom bound to a siliconatom with respect to the total silicon atoms in the compound (C) rangingfrom 0.3 to 0.95, and the “n” in the Formula 3 is in a range from 1 to2.
 19. The curable composition of claim 1, wherein the hydrogen siloxanecompound (C) has a weight average molecular weight of less than 1,000.20. The curable composition of claim 1, wherein a molar ratio of ahydrogen atom bound to a silicon atom in the hydrogen siloxane compoundwith respect to an alkenyl group bound to a silicon atom in the linearand crosslinked organosiloxane compounds ranges from 0.85 to 1.15. 21.The curable composition of claim 1, wherein the linear organosiloxanecompound, crosslinked organosiloxane compound and hydrogen siloxanecompound comprise at least one aryl group that is bound to a siliconatom.
 22. The curable composition of claim 20, satisfying Equations 1and 2 below:|X _((A)) −X _((B))|<0.4  [Equation 1]|X _((B)) −X _((C))|<0.4  [Equation 2] wherein X_((A)) represents amolar ratio of an aryl group bound to a silicon atom with respect to thetotal silicon atoms in the compound comprised in the polymerized product(A), X_((B)) represents a molar ratio of an aryl group bound to asilicon atom with respect to the total silicon atoms in the compound(B), and X_((C)) represents a molar ratio of an aryl group bound to asilicon atom with respect to the total silicon atoms in the compound(C).
 23. A semiconductor device that comprises a semiconductor elementencapsulated by an encapsulant that comprises the curable composition ofclaim 1 in a cured state.
 24. A light-emitting diode that comprises alight-emitting element encapsulated by an encapsulant that comprises thecurable composition of claim 1 in a cured state.
 25. A liquid crystaldisplay device that comprises the light-emitting diode of claim 24 in abacklight unit.
 26. A lighting device comprising the light-emittingdiode of claim 24.